The overall objective is to understand the genetics and genetic regulation of the Qa antigens encoded by the murine major histocompatibility complex. This complex has been a major concern to immunogeneticists for many years, initially because of its influence on tissue transplantation and more recently because of its involvement in determining the susceptibility to viral infections and successful cell-cell interactions during an immune response. The function of the Qa antigens and molecules has not been clearly defined although their unusual appearance on certain leukemia cells raises the possibility that they are involved in a normal or abnormal differentiation process. In this proposal, there are four specific aims: (1) to examine the allelism and polymorphism of genes within the Q subregion; (2) to determine the sites of recombination within and/or adjacent to the Q subregion, (3) to analyze the transcription and translation of Q subregions genes and (4) to study the control of the quantitative control of Q subregion gene products. Techniques to be used include molecular cloning and subcloning, isolation of genomic DNA and mRNA, Southern and Northern blot analyses, in vitro transcription and translation system, DNA mediated gene transfer, and DNA sequencing.